1. Field of Invention
The invention relates to a purification method and, in particular, to a method for purifying 1,4-bis(bromodifluoromethyl)benzene.
2. Related Art
Low dielectric-constant materials have smaller dielectric constants that can reduce the interference of currents among wires to increase the transmission functions inside integrated circuits (IC). It has become a trend to apply low dielectric-constant materials to various products. The speed of many advanced products can be increased by using low dielectric-constant materials. Products with low interference wires can reduce power consumption and increase the efficiency to dominate the market.
As reported in the U.S. Pat. No. 5,268,202, 1,4-bis(bromodifluoromethyl)benzene is one of the low dielectric-constant materials for IC. The compound can be synthesized from 1,4-bis(difluoromethyl)benzene by bromination. After the reaction, the 1,4-bis(bromodifluoromethyl)benzene crude product contains a little yet-dried solvent, reactant 1,4-bis(difluoromethyl)benzene, (1-bromodifluoromethyl 4-difluoromethyl)benzene, and other side products with higher or lower boiling points. However, these impurities have similar polarities as the main product. Therefore, it is hard to use a silica gel column to purify the 1,4-bis(bromodifluoromethyl)benzene.